CLEVELAND (UPI) — U.S. biologists say a Swinhoe’s soft-shell turtle — thought to be extinct in nature — has been found in northern Vietnam.

Vietnam researchers, sponsored by the Cleveland Metroparks Zoo and the Cleveland Zoological Society, identified the only known specimen living in the wild of the critically endangered giant soft-shell turtle Rafetus swinhoei.

After three years of searching lakes and wetlands along the Red River in northern Vietnam, field biologist Nguyen Xuan Thuan found the turtle at a lake just west of Hanoi. He photographed the turtle as it basked on the lake’s surface, allowing scientists to confirm the animal was the extremely rare Swinhoe’s turtle.

“This is an incredibly important discovery because the Swinhoe’s turtle is one of the most critically endangered species of turtle in the world,” said Doug Hendrie, the coordinator of Cleveland Metroparks Zoo’s Asian Turtle Program.

The largest freshwater turtle in the world, the Swinhoe’s soft-shell turtle — also know as the Shanghai soft-shell turtle or the Yangtze soft-shell turtle — can weigh up to 300 pounds, with some living more than 100 years.